Fix bug #62: Handle various kinds of relative URLs

This is still not a full URL parser as in http://url.spec.whatwg.org/
but should be good enough.
Add a 'minify' script.

The script requires bash and curl. It should work on any Unix-like system.
Don’t hard-code the header.
Merge pull request #129 from SimonSapin/issue62

Fix bug #62: Handle various kinds of relative URLs
Merge pull request #131 from SimonSapin/minify-script

Add a 'minify' script.
added viewport units plugin, CSS variables plugin
added viewport units plugin, CSS variables plugin
[amend] added viewport units plugin, CSS variables plugin
[amend] added viewport units plugin, CSS variables plugin
Support display: grid and inline-grid

New grid layout box model
http://dev.w3.org/csswg/css3-grid-layout/#grid-containers
landed in IE10 and will probably come with Chrome 27.

This adds new display property values 'grid' and 'inline-grid'
(and maybe later 'subgrid') that need to be prefixed.
Merge pull request #146 from ThomasWeiser/gh-pages

Support display: grid and inline-grid
Added min-content